SDSS (left) and LAMOST (right) density maps in the u − g vs. g − r plane. Identified DA/M binaries are shown as red open circles (blue open circles represent SEGUE and GAC DA/M binaries in the left and right panels, respectively). The solid black lines are colour-cuts defined for selecting DA/M binaries and excluding single main sequence stars. The number distribution of objects as a function of u − g and g − r within these cuts are provided in the upper and right panels, respectively.